The Fatome



What is the best source of fat on a ketogenic diet? The ketosphere is pretty segregated, almost in a religious manner, on this issue. Followers of the primal ‘we-evolved-to-eat mammoths, not vegetables’ faith often argue animal products, like red meat and dairy, are the superior fat sources. By extension, stable saturated fats become superior to more fragile and oxidation-prone monounsaturated fats or, worse yet, PUFAs! [Insert dramatic music here.] However, followers of the primal ‘Blue-zone-Anti-Alzheimer’s-Mediterranean’ faith, myself included, often lean towards believing that a well-formulated ketogenic diet should emphasize monounsaturated fats, from sources like olive oil and avocados, and Omega-3s, from fatty fish. Plus, my religion holds, the planty-veggy fibers, polyphenols, and antioxidants promote good microbiome and overall health!


Of course, please know, the religion analogy is in jest. The more nuanced point is this: we come to the discussion with our own biases, often informed by our personal, and very legitimate, health journeys. For example, I’m at high-risk for Alzheimer’s disease and happen to have always loved fish. I’m sure that biases me towards the latter of the two “faiths” mentioned above. But this piece isn’t about sticking to our guns or mob mentality; it’s about thinking scientifically to come up with an informed best guess at what the best source of fat is on a ketogenic diet.


The punchline, inevitably (spoiler alert), is this: there is no single best fat! The best ketogenic diet almost certainly relies on an optimized balance of different fat sources – not too much of any one good thing, rather just enough of all the good things! 


So, let’s begin the analysis by “operationalizing our variables,” i.e. let’s decide what factors are the most important to consider.


  1. Long-Chain Saturated Fatty Acid Profile


The jury is still out on saturated fatty acids. Personally, I tend to believe that, provided you are on a ketogenic diet, they are stable and healthy in moderation. However, there are exceptions. Given my ApoE genotype (E4/E4), along with some other bits and pieces I know about my genetics and metabolic profile, I am convinced I am among the exceptions. Because most of us don’t know, in detail, how we handle saturated fats as individuals, it may be worth playing a conservative hand and not overdoing saturated fat. That is your choice. I realize this is a charged topic.


More to the point, not all long-chain saturated fatty acids are equal! Long-chain saturated fatty acids differ in the length of their tails, from 12 carbons to 22 carbons. The four fatty acids I want to focus on are the 12, 14, 16, and 18-carbon fatty acids, lauric acid, myristic acid, palmitic acid, and stearic acid. In general, lauric acid, myristic acid, and palmitic acid can all decrease the expression of LDL receptors on your liver. This is not bad because it can increase LDL, it’s potentially bad because of how it can increase LDL. You see, by decreasing LDL uptake at the liver, you decrease LDL turnover and LDL in the blood has more time to get oxidized, condense, and become atherogenic. By contrast, steric acid does not decrease LDL receptor expression on the liver. Therefore, saturated fat sources that have a higher stearic acid-to-(palmitic acid + myristic acid) ratio may, in some people, be preferable. If you take a look at the compare and contrast table, this would imply cacao (chocolate) saturated fat may be better than fat from dairy (ghee) or red meat.


I left lauric acid out of the above ratio/formula because it’s somewhat of a black sheep. Some consider it a long-chain fatty acid and others consider it a medium-chain fatty acid. It’s a complex issue. The point that is most compelling to me is that lauric acid is present, largely, in coconut oil, and virgin coconut oil (not refined, only virgin) appears to improve serum lipid profiles, having no impact on LDL and increasing HDL. This may be because of the polyphenols in virgin coconut oil, and/or its probiotic properties, outweigh the LDL receptor effect. I’m not sure. Regardless, it would be impractical to lump in lauric acid with myristic and palmitic acid, as least as it relates to people on a ketogenic diet.


  1. MCTs


I won’t spend much time on medium-chain triglycerides (MCTs), other than to make three points: (i) MCTs go straight to the liver, rather than into systemic circulation, and get used as more immediate fuel and get turned  into ketones. This is presumed to be good. (ii) Coconut oil is praised for its MCT content, but it’s only about 16% MCTs. Sorry. (iii) All-in-all, guzzling C8 or coconut oil will not have a huge impact on your ketone levels.


As an aside for cheese lovers, C8 caprylic acid is named after the Latin for goat (“capra”) because it is caprylic acid that gives goat dairy its goaty flavor.


  1. MUFAs


Monounsaturated fatty acids, and their primary sources (olive oil, avocados, and macadamia nuts), many consider to be superfoods. I tend to agree. Real extra virgin olive oil is perhaps the best fat source of polyphenols and has more health benefits than I could list here. Avocados don’t have quite as many polyphenols, but avocados themselves are packed with healthy fibers and avocado oil has a great smoke point for cooking (more below). However, olive oil and avocado oil have a slight potential drawback: they are each 10-14% Omega-6. These proinflammatory essential fatty acids are fine (and unavoidable) to consume in moderation, but if you are like me and can consume over 1.5 Liters of olive oil per week, those Omega-6 can add up, potentially contributing to higher oxidized LDL levels. So, if you’re Mediterranean-Keto, what do you do? Here are two suggestions: (i) Add in more macadamia nut and macadamia nut oil, which are rich in MUFAs, but much lower in Omega-6. (ii) I personally found that including some, but not too much, virgin coconut oil and raw (must be raw) organic coconut butter improved my oxidized LDL levels.


Most of the MUFAs in your diet will be oleic acid. Oleic acid is awesome because it gets converted into a metabolite called oleoylethanolamide (OEA) which activates the fat-burning transcription factor PPARα and stimulates TRPV1 receptors on the vagus nerve to make you feel full. There is, however, another (rarer) MUFA worth mentioning: palmitoleic acid, also known as Omega-7. Palmitoleic acid is richest in macadamia nuts, synergizes with Omega-3s (found in fish), and can help to improve serum lipids and insulin sensitivity.


  1. Omega-3


I have one point to make here: Eat Fatty Fish. Period. Fatty Fish (SMASH: Salmon, Mackerel, Anchovies, Sardines, Herring) are your sources of the Omega-3 fatty acids, EPA and DHA. You need adequate EPA and DHA for optimal health. That’s not really a point that’s in dispute.


Land sources of Omega-3s, such as flax seeds and walnuts, only contain ALA. ALA can be converted into EPA and DHA, but only at extremely low levels. Therefore, you either need to have some fish in your diet or supplement with EPA and DHA in some form. This doesn’t need to be fish oils, if you are vegetarian. Fish get their EPA and DHA from eating marine algae, so there are also algae-based EPA and DHA supplements available as well.


  1. Smoke Points


You ruin an oil if you overheat it. The most heat-resistant fat sources are avocado oil and ghee. Select your favorite (or alternate between both) depending on your personal preference. Most other oils, including olive oil, can be used for low-temperature cooking (see compare and contrast table). Never overheat fish or flax seed oils as they are among the most heat sensitive.


  1. Other Considerations: Probiotic Effects, Dairy Sources, & Whole Foods vs. Oils


I hope we can agree that it’s not just about IIFYM (“if it fits your macros”), nor it is simply about IIFYFAP (“if it fits your fatty acid profile”). Here are some additional factors to consider:


(i) Certain fat sources come with probiotic effects. Lauric acid may help to kill off bad bacteria in your gut, while promoting good bacteria. Similarly, the fibers found in avocados and bacteria found in blue cheeses may each help to improve microbiome health.


(ii) Since I mentioned blue cheese (my favorite is Roquefort), let’s talk dairy. In general, non-cow dairy sources are best. This is because cow dairy contains what’s known as “A1 casein,” which gets turned into an opioid in your gut that is proinflammatory and can cause constipation. My hierarchy, all things considered, is goat, sheep, buffalo, and cow, in that order. If you can find a raw goat’s milk blue cheese, you’ve hit the cheese holy grail.


(iii) Consider this: nature often packages fats in whole foods in a protective manner. For example, the Omega-3s in salmon are healthy but fragile. That’s why wild salmon are pink! Wait, what?! Yes. That’s why wild salmon are pink. When wild salmon are on their upstream marathon journey to breed, and exercising their little tails off, they generate a lot of oxidative stress. As a result, their bodies make astaxanthin, a potent antioxidant that protects the valuable Omega-3 fats. When you eat wild salmon, you get the Omega-3 and astaxanthin (its bodyguard). When you eat only fish oil, you often don’t. That’s just one of hundreds of examples.


So, let’s return to the starting question: What is the best source of fat on a ketogenic diet? I hope by now you understand that the answer is not so simple. In fact, I want to coin a term… the “fat-ome.” We have our genomes, microbiomes, metabolomes, transcriptomes, why not a “fatome”? i.e. the unique balance of fats we each consume in our diets? Since all of our other “omes” are unique, it makes sense that each of us have our own best fatome. Therefore, I won’t tell you, in detail, what fats are best for you, but will leave you with some questions to help you reflect on what you just read:


Like saturated fat? Is it worth considering that not all saturated fats are created equal? Is it worth considering the stearic acid/(myristic + palmitic) ratio?


Is it worth thinking deeply about coconut oil? In you, as an individual, how do the saturated fats, especially lauric acid, and 16% MCTs, balance in your fatome? 


Are you Mediterranean-Keto? If so, could you be overconsuming olive oil and avocado oil? It is worth checking out macadamia nut oil and/or incorporating just a bit more saturated fat (virgin coconut oil or raw organic coconut butter)?


Are you eating fatty fish, at least twice per week? The answer should either be, “yes,” or, “I supplement.” About this I do feel strongly.


What oils do you use for cooking?


Are your fat sources mostly from extracted oils, or do they include whole foods? 


Are your fats “extra virgin” (olive oil), virgin (coconut oil), and/or “raw” (nuts, coconuts, and dairy)?


And, finally, what self-experiments can you do to begin your quest to find your best fatome?



Nicholas Norwitz

*The views and opinions expressed herein are those of the author and do not necessarily reflect the views of, its affiliates, or its employees.